Analgesic drugs are known, that are nonnarcotic analgesics by their mechanism of action, such as acetylsalicylic acid, metamizole and others [1]. Data on activity in acetic acid induced writhing test (ED50) and acute toxicity (LD50) of the known drugs are presented in [2] and in Table 1.
TABLE 1Toxicity and analgesic action of the known drugs [2].DrugED50, mg/kgLD50, mg/kgAcetylsalicylic acid1551600Metamizole553300Sodium diclofenac5370
The disadvantage of acetylsalicylic acid is low activity and gastrointestinal toxicity; metamizole may induce hematopoiesis disorders, up to agranulocytosis.
Diclofenac sodium [3] was chosen as a prototype.
The disadvantages of sodium diclofenac are adverse gastrointestinal effects (gastrointestinal toxicity).